Using a novel patient-specific stem cell-based therapy, researchers at the National Eye Institute (NEI) prevented blindness in animal models of geographic atrophy, the advanced "dry" form of age-related macular degeneration (AMD), which is a leading cause of vision loss among people age 65 and older. The protocols established by the animal study, published January 16 in Science Translational Medicine (STM), set the stage for a first-in-human clinical trial testing the therapy in people with geographic atrophy, for which there is currently no treatment.
"If the clinical trial moves forward, it would be the first ever to test a stem cell-based therapy derived from induced pluripotent stem cells (iPSC) for treating a disease," said Kapil Bharti, Ph.D., a Stadtman Investigator and head of the NEI Unit on Ocular and Stem Cell Translational Research. Bharti was the lead investigator for the animal-model study published in STM. The NEI is part of the National Institutes of Health.
The therapy involves taking a patient’s blood cells and, in a lab, converting them into iPS cells, which can become any type of cell in the body. The iPS cells are programmed to become retinal pigment epithelial cells, the type of cell that dies early in the geographic atrophy stage of macular degeneration. RPE cells nurture photoreceptors, the light-sensing cells in the retina. In geographic atrophy, once RPE cells die, photoreceptors eventually also die, resulting in blindness. The therapy is an attempt to shore up the health of remaining photoreceptors by replacing dying RPE with iPSC-derived RPE.

Kohske Takahashi
We report a novel illusion––curvature blindness illusion: a wavy line is perceived as a zigzag line. The following are required for this illusion to occur. First, the luminance contrast polarity of the wavy line against the background is reversed at the turning points. Second, the curvature of the wavy line is somewhat low; the right angle is too steep to be perceived as an illusion. This illusion implies that, in order to perceive a gentle curve, it is necessary to satisfy more conditions––constant contrast polarity––than perceiving an obtuse corner. It is notable that observers exactly “see” an illusory zigzag line against a physically wavy line, rather than have an impaired perception. We propose that the underlying mechanisms for the gentle curve perception and those of obtuse corner perception are competing with each other in an imbalanced way and the percepts of corner might be dominant in the visual system.
Perception of contour and shape is one of basic functions of vision. To this end, visual system processes information in a hierarchical way; first it extracts local orientations, then it integrates the local orientations into intermediate representations of contour, and finally it forms global shape percepts (Loffler, 2008). The intermediate representation of contour would include concavity, convexity, corner angle, curvature, and so forth. Although it is obvious that the physical shape is determined by combination of the local orientations, perceptual shape is susceptible to several factors. Accordingly, as visual illusions demonstrate, percepts are not necessarily veridical. For example, the café wall illusion (Pierce, 1898) demonstrates that parallel horizontal lines are perceived as different angles to each other.

Scientists at the National Eye Institute (NEI) have found that neurons in the superior colliculus, an ancient midbrain structure found in all vertebrates, are key players in allowing us to detect visual objects and events. This structure doesn’t help us recognize what the specific object or event is; instead, it’s the part of the brain that decides something is there at all. By comparing brain activity recorded from the right and left superior colliculi at the same time, the researchers were able to predict whether an animal was seeing an event. The findings were published today in the journal Nature Neuroscience. NEI is part of the National Institutes of Health.
Perceiving objects in our environment requires not just the eyes, but also the brain’s ability to filter information, classify it, and then understand or decide that an object is actually there. Each step is handled by different parts of the brain, from the eye’s light-sensing retina to the visual cortex and the superior colliculus. For events or objects that are difficult to see (a gray chair in a dark room, for example), small changes in the amount of visual information available and recorded in the brain can be the difference between tripping over the chair or successfully avoiding it. This new study shows that this process – deciding that an object is present or that an event has occurred in the visual field – is handled by the superior colliculus.
“While we’ve known for a long time that the superior colliculus is involved in perception, we really wanted to know exactly how this part of the brain controls the perceptual choice, and find a way to describe that mechanism with a mathematical model,” said James Herman, Ph.D., lead author of the study.

Scientists funded by the National Eye Institute (NEI) report a novel gene therapy that halts vision loss in a canine model of a blinding condition called autosomal dominant retinitis pigmentosa (adRP). The strategy could one day be used to slow or prevent vision loss in people with the disease. NEI is part of the National Institutes of Health.
“We’ve developed and shown proof-of-concept for a gene therapy for one of the most common forms of retinitis pigmentosa,” said William Beltran, D.V.M., Ph.D., of the University of Pennsylvania School of Veterinary Medicine, Philadelphia, a lead author of the study, which appears online today in the Proceedings of the National Academy of Sciences.
Retinitis pigmentosa refers to a group of rare genetic disorders that damage light-sensing cells in the retina known as photoreceptors. Rod photoreceptor cells enable vision in low light and require a protein called rhodopsin for their light-sensing ability. People with adRP caused by mutations in the rhodopsin gene usually have one good copy of the gene and a second, mutated copy that codes for an abnormal rhodopsin protein. The abnormal rhodopsin is often toxic, slowly killing the rod cells. As the photoreceptors die, vision deteriorates over years or decades. Scientists have identified more than 150 rhodopsin mutations that cause adRP, challenging efforts to develop effective therapies.
Beltran generated a gene therapy construct that knocks down the rod cells’ ability to produce rhodopsin using a technology known as shRNA (short-hairpin RNA) interference.
Gene therapy introduces genetic material, like shRNA, into cells to compensate for abnormal genes or to make a beneficial protein. Often adapted from viruses, vectors are engineered to effectively deliver this genetic material into cells without causing disease.